Ways To Improve Response

[vorse]

I'm looking for information on cam choices vs turbo size for a car that is aiming to make 350-400 kW to come on boost early in the rev range around 3000 rpm if not sooner ive looked at a fair few dyno graphs but not all have the RPM figures so im only guessing

ive been looking at -5s vs a Precision 6262 or even -7s to try and get the response im chasing

i would also like to know what parts i should be factoring in to try and achieve my goal the motor is going to be a 2.6 running 98

im also looking for advice regarding exhaust manifold and dump pipe sizing eg will going a smaller size improve spool time vs larger piping for more up top

any help would be appreciated as i seem to mill over this in my head on a daily basis at the moment

[AngryRB]

I think bigger dump is better even if its just a placebo effect, and hook it up with a good boost controller and spike it early, ethanol or meth and alot of ignition timing obviously would help, twin scroll housing etc. My GTX woke up with ethanol and a boost spike, not sure if HPC coating the manifold and housing contributed but a good idea too

Edited February 5, 2013 by AngryRBGTX

[Piggaz]

Stroker

High comp

E85

3 big things your setup doesn't seem to have. 350 plus might be a bit of a stretch on -7's without nailing everything.

A big exhaust goes along way. No "ups and downs" in size too.

What are you doing with the car?

Edit: -7's not -9's. Err.

[vorse]

streeter capable of holding its own at track days i dont know enough about stokers to invest but would like to learn if you can point me in the right direction

would the -9s be applicable on a stroked setup? if seen good results from the precison in the reigion of 3000 but that was on e85 comments?

[R31Nismoid]

If you wanna hold your own at track days you'll be spending more time and money in suspension, geometry, brakes, rubber, diffs, transfer case etc etc. Over worrying about the outright power. There is a solid 10k in those things, more if you get even more serious.

Prime example here in Vic is everyone said you needed 380rwkw to get a GTR into the 'teens' at Sandown. Then one day it was done solidly with 330rwkw and full weight. It came down to the things mentioned earlier - and a driver with experience and knowledge of his car

Put -9s on (so its still responsive around town), and spend time/money in getting the car sorted in the more important areas - especially seat time, as you'll chop times consistently for years In most cases especially as you develop the car. Enjoy milling over that for the next month lol

[Count Grantleyish]

aiming to make 350-400 kW to come on boost early in the rev range around 3000 rpm if not sooner

Honestly, it's impossible.

My -7s doesn't make full boost at this sort of revs. Nor did the -9s did.

[blk94r33]

400kw, 2.6lt, full boost by 3k, pick two......

[Lithium]

Come on boost around 3000rpm, no problem. Full boost before 4000rpm - more of a problem but maybe possible with something like an EFR7670, E85, high compression etc.

[SiR_RB]

Maybe 2.8 high comp stroker with -9's and ethanol will be adequate ?

[sky30]

400kw, 2.6lt, full boost by 3k, pick two......

What turbos ?

[vorse]

asking for advice about what configuration will come closest to what im looking for im more will to compromise on the power figure but i want to get as close as possible to the 400 mark

[GTSBoy]

A specific answer.......smaller diameter primaries in the exhaust manifold will obviously give you the best response. There is a mention in one of the other threads very recently about a small bore 6boost manifold (and Kyle's unwillingness to make any/too many of them) that gave better response. You would want to emulate something like that. Most aftermarket manifolds have an emphasis on being big enough to support as much power as anyone could want. They all claim to try to deliver as much response as possible, but I'm sure that if you were willing to put up with a bit more restriction of really high flows you could further enhance the bottom end pick up.

cheers

[R31Nismoid]

^ and with good reason, making them response driven from the exhaust side maybe hurts too much in the top end?

You could build the head more specifically for response, but expect once again the top end to hurt (and you wouldn't make that call if you put -5s on).

asking for advice about what configuration will come closest to what im looking for im more will to compromise on the power figure but i want to get as close as possible to the 400 mark

Well on 98 & 2.6ltr, you have little choice as it's a tall ask even for -5s. You'll get to 370rwkw but you aren't going to have the response you want.

-9s will give you 330rwkw pretty much as max and will get as close to your response aim.

Many threads have sorta gone along this way and 10 pages later - it's simply a case of you need to make the choice. This post summed it perfect:

400kw, 2.6lt, full boost by 3k, pick two......

[vorse]

ok so if i accept the fact that im going to have to stroke the motor what would i be looking at in the way of supporting mods so i can get everything in place before i start to build the motor?

what have you guys tried that works i want to do this once and do it right

[scotty nm35]

A specific answer.......smaller diameter primaries in the exhaust manifold will obviously give you the best response. There is a mention in one of the other threads very recently about a small bore 6boost manifold (and Kyle's unwillingness to make any/too many of them) that gave better response. You would want to emulate something like that. Most aftermarket manifolds have an emphasis on being big enough to support as much power as anyone could want. They all claim to try to deliver as much response as possible, but I'm sure that if you were willing to put up with a bit more restriction of really high flows you could further enhance the bottom end pick up.

cheers

^^ this.

I doubt slightly smaller diameter runners would hurt top end on a 400kw e85 build. What sort of power do the standard 6boobs flow?

[R31Nismoid]

It's always interesting as the turbine housing is usually always where the restriction is, so promoting flow outta the head larger/smaller runners - would be interesting to see how much response you would actually get.

ok so if i accept the fact that im going to have to stroke the motor what would i be looking at in the way of supporting mods so i can get everything in place before i start to build the motor?

what have you guys tried that works i want to do this once and do it right

Well nothing really. Just bolt on turbos and wait until you do the motor.

If it's 3-4 years away then why put wear and tear on motor parts now?

Better to do it all at once, so it's fresh, and no weak/worn links in the build.

So seriously, do all the drivetrain stuff I said earlier. Chop the lap times down hard as you can (there is 10k there as i said). Then once you are ready, do the build and then continue development... By which point you'll know a hell of a lot more than you do now, and also be able to drive it much better to actually notice how small changes affect the car. That knowledge doesn't come overnight

[vorse]

so -5s a decent exhaust a tune some injectors and a pump

can any one point me in the right direction and ball park me on the cost of a 2.8 stroker build?

[R31Nismoid]

^ yep pretty much! AFMs too (if you dont have).

Stroker - 10-14k. That is bottom end, also giving the head a full reco and cleaning up - plus all the labour and everything else.

[vorse]

car is stock as a rock with 77 thousand on the clock so it needs love

who does a decent stroker so i can do some research ?

[Piggaz]

HKS, Tomei ... 2.8 - 77.7mm

Brian Crower is a 2.9 - 79 mm IIRC

Rb30 - 85mm